The F543 octal transceiver contains two sets of D-type latches for temporary storage of data flowing in either direction. Separate Latch Enable and Output Enable inputs are provided for each register to permit independent control of inputting and outputting in either direction of data flow. The A outputs are guaranteed to sink 24 mA while the B outputs are rated for 64 mA.

The F543 contains two sets of eight D-type latches, with separate input and output controls for each set. For data flow from to B, for example, the A-to-B Enable (CEAB) input must be LOW in order to enter data from A0­A7 or take data from B0­B7, as indicated in the Data I/O Control Table. With CEAB LOW, a LOW signal on the A-to-B Latch Enable (LEAB) input makes the A-to-B latches transparent; a subsequent LOW-to-HIGH transition of the LEAB signal puts the A latches in the storage mode and their outputs no longer change with the A inputs. With CEAB and OEAB both LOW, the 3-STATE B output buffers are active and reflect the data present at the output of the A latches. Control of data flow from A is similar, but using the CEBA, LEBA and OEBA inputs.

Note 1: Absolute maximum ratings are values beyond which the device may be damaged or have its useful life impaired. Functional operation under these conditions is not implied. Note 2: Either voltage limit or current limit is sufficient to protect inputs.